Switch



June 6, 1933.

A. ALSAKER El AL SWITCH Filed Sept. 27, 1926 4 Sheets-Sheet l UZZf g u%%6;ker 5+5? Mi /mm.

June 6, 1933. A. ALSAKER EIAL 1,912,615

swn-cn Filed Sept. 27, 1926 -4 Sheets-Sheet 2 Eric \Afprdhem. W M

June 6; 1933. A. ALSAKER El AL SWITCH Filed Sept. 27. 1926 4 Sheets-Sheet 3 June 6, 1933. ALSAKER ET-AL V swncn Filed Sept. 27. 1926 Patented June 6, 1933 UNITED STATES PATENT OFFICE ALFRED ALSAKEB AND ERIC NORDHTEH, OI CHICAGO, ILLINOIS, ASSIGNOBS TO THE DELTA-STAR ELECTRIC COMZPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS SWITCH Application med September 27, 1926. Serial No. 137,925.

or the like, one on either side thereof; and

when so used, they are termed disconnect switches, and are adapted to be opened after the oil switch is opened so that the latter or any portion of the line immediately adjoining the. same may be worked on with safety.

Disconnect switches are usually operated in gangs making it desirable if not essential that the blades be opened and closed in-vertical planes so as not to interfere with each other. Furthermore switches of this type are usually used under conditions wherein they are exposed to the elements and the blade is apt to stick in the contact due to ice accumulation or .corrosion. Three insulator switches have been found to be most efficient as disconnect switches and accordingly this invention aims to provide a switch of this type in which the blade is operated in a vertical plane in a manner which affords a maxi mum of leverage for breaking the corrosion hold of the contact.

To carry out our invention we employ a switch including a plurality of insulator supports one of which may be rotated and 1S operatively connected to a switch blade carriage for rocking the same to open or close the switch. A switch blade is pivotally mounted on' the outer end of the carriage and acts together therewith as an extensible switch arm. A torsion spring is provided between the carriage and blade on the pivot thereof for holding the arm in extended position and is so mounted that in closing the switch it will act with the inertia of the blade to cause the latter to fall full into a suitable switch contact terminal.

A spring bumper is provided adjacent the contact terminal to break the fall of the blade and latches are mounted on the bumper to cooperate with the blade for preventing the latter from being thrown open either from excessive slamming or the magnetic effect of a large flow of current as from short circuit.

When the carriage is rocked to openthe switch, the blade will pivot on said carriage against the action of said spring and the switch arm will thus be contracted substantially in the direction of its length until released from engagement with the contact terminal. As soon as the arm has been with.- drawn from the contact, the torsion spring will actuate it to extended position away from said contact and the continued movement of the carriage will swing the arm farther away from said contact.

'The. initial contraction of the switch arm in the direction of its length will act both to loosen the blade in the contact to permit a subsequent swinging movement therefrom and also to release the said blade from engagement with the latches on the spring view of the right hand portion of the switch;

Fig. 4 is a fragmentary vertical section taken at the line 4-4 of Fig. 3;

Fig. 5 is a fragmentary horizontal section taken at the line 55 of Fig. 4;

Fig. 6 is an enlarged vertical view partly in section taken at the line 6-6 of Fig. 1;

Fig. 7 is an enlarged vertical sectional view showing parts in elevation and taken at the line 77 of Fig. 1;

Fig. 8 is an enlarged detail fragmentary view showing the left hand portion of the switch mechanism as viewed in Figure 1;

Fig. 9 is a plan view of Figure 8;

Fig. 10 is a detail, fragmentary side view with parts removed showing a modified form of spring bumper and locking mechanism for the blade; and

Fig. 11 is a similar view from the right of Figure 10.

Referring to the drawings more particularly in which like reference numerals des- 11 and 12 serve to support respectively stems 13 and 14, and their respective insulators 15 and 16. Also mounted on the beam 7 10 intermediate of the bases 11 and 12 is a bearin member 17 of a rotary insulator 18 similar to that shown and described in 1 nt 1,759,149 granted May 20, 1930 to Alfred Alsaker, and having a shaft 19 which extends through the bearing 17 and the beam '10.. The lower end of the shaft \19 is provided with a suitable squared or,hexed portion adapted to cooperate with an operating crank or extension 20 for rotating the insulator 18.

The insulators 15, 16 and 18 each have connected on their respective upper ends metal caps 21, 22 and 23.

Rigidly secured to the rotary insulator 18 on top of the cap 23 is a crank including a block 24. A stud 24a is provided on the cap 23 offset from the center thereof and extends into a blind recess in the bottom of the block 24 to prevent the latter from rotating relative to said cap. The block 24 has a raised shoulder 25 adjacent one edge thereof and is secured to the cap 23 by a screw 26. A detachable upper plate 27 is screwed on the shoulder 25 and has a central upwardly extending journal 28 thereon. Parts 24, 25 and 27 may be made integral if desired. A pin 29 is journalled between the plate 25 and the base of the block 24 and is oflset from the center of said block. The pin 29 is provided with a cro$ head 30 which is journalled-in a bifurcated member 31 ofa connecting rod to be hereinafter described.

A metallic housing 32 extends from above the cap 22 to above the cap 23. This housing may be made in sections suitably bolted together. This is particularly adaptable to different spacings of the insulators 16 and 18. In the embodiment shown the upper side of the housing 32 is apertured and is provided with a hub surrounding such aperture, said hub acting as a bearing for the journal 28. The bottom ed e of the hub 33 rests upon a suitable sho der 34 on the plate 27 at the base of the journal 28 thereon; The journal 28 and shoulder 34 at the base thereof thus act to support the left end of the housing 32. A cap 35 is held on the top of the journal 28- by a bolt 36 and acts to retain the left end of the housing 32. The right end of the housing 32 is supported by a bolt 37 which extends therethrough into the center of the cap 22. The upper side of the housing 32 is also provided with an aperture 38 and transversely spaced integral bearing lugs 39 at opposite sides of said aperture for supporting a transverse pin 40.

A blade carriage 41 consisting of a pair of transversely spaced parallel double arms v46 mounted on a transverse pin 47 connecting the lower ends of the arms 42. The member=46 has a vertical pin 48 thereon; which extends through said bifurcated member 45. The-ends of the rod 44 are oppo-' sitely threaded and are provided with lock nuts 49 so thatsaid rod may be adjusted. It will thus be seen that the carriage 41' may be rocked by rotating 'the insulator 18 through the extension 20'or a suitable crank:

The upper end of the carriage 41 is apertured to pivotally support the right end of a switch blade 50 which will be hereinafter described more specifically and which is adapted'to fit in a contact terminal 51 mounted as will be hereinafter explained on the insulator 15. This switch arm 50' may be made up of tubing suitablyflattened at the forward end and fitted to the rear supporting brackets 52. The rear end of the blade is provided with opposite transversely disposed brackets 52 and 53. The brackets 52 and 53 are clamped on either side of the blade 50 and are provided with arms 54 and 55 respectively, which extend on either side of the carriage 41 and are pivotally secured thereto by means of a transverse pin 56 connecting said arms and extending through the upper ends of the arms 42 through suitable apertures therein. A transverse stop pin 57 is supported between the arms 54 and 55 and a second stop pin 58 is supported between the arms 42 of thecarriage. A torsion spring 59 surrounds the pin 56, the ends of said spring being connected beneath the respective pins 57 and 58 and acting to keep the blade 50 extended upwardly about the pin 56. The spring 59 is normally compressed enough to keep the blade 50 extended against the weight and inertia thereof with the pin 57 abutting projecting stops 60 on the upper ends of the arms 42. When the carriage 41 is rocked about the pin 40, as previously described, the upper end of said carriage including the pin 5, will act to move the blade 50 to the right. The movement of the blade 50 to the right as the carriage 41 is rocked about the in 40 is limited by a second pair of proecting stops 61 integral with the arms 42 and angularly spaced from the stops 60. As the carriage 41 continues to rock about the pin 40, the stop 61 in case the spring 59 fails to act on the blade 50 in the meantime will engagebeneath the in 57 and cause the blade 50 to move angu arly with the said carriage. During the longitudinal movement of the blade 50, the sprin 59 is com prcssedand as soon as said bla e leaves the contact 51, the said spring will act on said blade and cause the same to move relative to the carriage 41 until the pin 57 again abuts the stops 60, thus giving said blade a quick initial movement away from the contact. The blade 50 taken together with the carriage 41 constitutes a compound blade that is swingable about the pin 40 as a center. The compound blade comprising the mem bers 50 and 41is extensible and retractable, that is, the distance from the remote end of the blade portion 50 to the pin 40 increases or decreases de ending upon the instantaneous position 0 the compound blade about its pivot pin 40. By providing for the substantial longitudinal movement of'the blade 50 to the right before the lateral or swinging motion thereof from the contact 51, said blade is initially loosened in said contact from any contact pressure, corrosion pressure, or ice, and much less force is required to open the switch than would be required without such longitudinal movement.

. tained' in its maximum extended position with the pin 57 abutting the stops 60as the inertia of said blade acts with the spring 59 to maintain said blade in such position. The blade 50 thus strikes full into the contact 51 when the switch is closed. The blade may be. said to be resiliently mounted with respect to the support at the pin 40 since by reason of the pivot 5 and the spring 59 the blade has a limited motion with respect to the pivot, the spring returning the blade to its normal relative position when' the force that caused the displacement is released.

As shown in Figures 3, and 9, the blade 50 here shown consists more specifically of an elongated reinforcing iron strip 61 on either side of which is secured a copper strip 62. The copper strip 62 extends beyond the reinforcing bar 61 at the free end of the blade and are brought together to form a thinner contacting portion 63. The portion 63 is adapted to afford contact between the blade 50 and the contact 51. The construction of thisblade may be varied as above indicated.

.The right of the blade 50 has secured thereon, one onv either side thereof, between the respective brackets 52 and 53 and said blade, a strip of copper braid 64. The braids 64 extend through the carriage 41 and have,

their lower ends brought together and bolted to a terminal lug 65 mounted on a projection 66 integral with the housing 32 at the right hand lower edge thereof.

The contact 51 comprises more specifically contact blocks 67 and 68 which are made from seamless hard drawn, copper tubing flattened over flexible copper braids 69 and 70 respectively, and flared outwardly at their upper ends to form blade guides. The blocks 67 and 68 are sup orted respectively by rugged flat sprin s 1 and 72 mounted on an adapter plate 3 rigidly secured to the cap 21. The blocks 67 and 68 are each connected to their respective springs 71 and 72 by a pair of vertically spaced pins 74 and 75. The pins 7 4 are riveted at their inner ends to their respective blocks 67 and 68 and extend outwardly into vertically slotted apertures 76 in their corresponding springs 71 and 72. The pins are likewise riveted to their respective blocks 67 and 68 below the pins 74 and extend outwardly to engage'loosely in apertures in their corresponding springs 71 and 72. Semi-spherical annular bearings 77 are provided, one on each pin 75 and co-act with the edge of the aperture for said pin to permit a slight universal movement of the contact blocks 67 and 68. The chief function of pins 74 is to prevent rotary movement of blocks about pins 75. Obviously instead of flat springs 71 we may employ coil springs or other means.

The braids 69 and 70 are brought together at their lower ends and are connected to a terminal lug 70a bolted to the plate 73.

Means are provided for breaking the fall of the blade and preventing it from being thrown out of contact by excessive slamming or magnetic effect. or this purpose, a threaded stem 78 is provided which extends through the adapter plate 73 into the top of the cap 21. A jam nut 79 acts to hold the stem 78 against working off said cap 21 and also acts to hold the plate 73 on said cap. The cap 21 and plate 73 may be connected with dowel pins when a single center bolt is employed. A slidable cap 80 is mounted on the upper end of the stem 78 and is provided with a transverse pin 81 on which is mounted a pair of latches 82, one on either side of said cap. A recess 83 is cut out of the side of the stem 78' for slidably receiving the transverse pin 81. The ends of the recess 83 act as stops for limiting the upper and lower movement of thecap 80. A helical spring 84 surrounds the stem 78 between the lower edge of the cap 80 and the jam nut 79. The spring 84 normally acts to hold the cap 80 upwardly with the pin 81 therein abutting the upper end of the recess 83. The cap 80 may thus act to break the fall of the blade when the switch is closed. The lower edges of the latches 82 project downwardly to the left of the pin 81 and abut a washer 85 below the ca 80 such projections acting to move the late es clockwise as viewed in Figure 8. A cross bar 86 connects the latches 82 and abuts the side of the cap 80 acting as a stop to limit the clockwise movement of said latches. A transverse pin 87 extends through the blade 50 near the left hand end thereof and is ada ted to strike the latches 82 as the switch is c osed. When the pin 87 strikes the top of the latches 82 as the switch is closed, said latches will momentarily move to the left tem orarily compressing the spring 84 to permit said pm to pass sald latches and hook thereunder.

In Figs. 10 and 11 there is shown a modified form of s ring bumper and latch mechanism for brea ing the fall of the plate and preventing it from being thrown out of contact. In this embodiment the internal diameter of the washer 85a similar to the washer 85 is enlarged, as well as the diameter of the washer itself so that the spring 84a acts directly on the bottom of the cap 80a of the bumper. A separate spring 100 concentrlc with the spring 84a is provided outside thereof and acts on the washer 85a to move the latches 82a in a counterclockwise direction. The internal diameter of the washer 85a is sufiiciently eat to permit the cap 80a to extend theret 11011 h when the latter is struck 1 The horns 88 and 89 are each provi by the blade. uch a construction insures that the latches 82a will be actuated to engage with the pins 87 of the blade even during the depression of the cap 80a by the throw of the blade. This is accomplished by the provision of the independent springs 84 and 100 for the bumper and latches respectively.

Arcing horns are provided consisting of a pair of upright horns 88 and 89 adjustably mounted in transversely s aced apertured lugs 90 and 91 on the a apter plate 73. Set screws are provided in the lugs 90 and 91 to adjustably secure the horns 88 and 89 respectively in any suitable vertical (position.

edwith a lower vertical portion and an upward outwardly flared portion. The upward outwardly flared portion of each horn is joined by a horizontal portion to the lower vertical portion thereof. The horizontal portions of each horn act as shoulders and are in juxtaposed relation with each other.

Arcing fingers are provided for contacting the arcing horns 88 and 89. An inverted U- shape bracket 92 is pivoted through means of a pin 93 on top of the blade 50 and is provided with a pair of angularly spaced projections 94 and 95 which are adapted to engage with a stop pin 96 on blade 50 to limit the pivotal movement of said bracket thereon. A pair 99 is mounted on the blade 50 and is connected to the bracket 92 for pivoting the same and causing the proJection 94 to normall abut the pin 96 w en the switch is open. X torsion or other spring might be used instead of the tension spring 99. When the switch is closed the fingers 97 and 98 will contact the arcing horns 88 and 89 at their upward outwardly flaring portion and upon abutting the shoulder formed by the transverse portions of said horns, said fingers will pivot upwardly until the projection 95 abuts the pm 96. The arcing horns will thus contact with the fingers 97 upon the closing of the switch before the blade 50 actually comes in contact with the contact 51 and in addition, said horns and said fingers will remain in contact after said blades and said contacts 51 have separated upon the opening of the switch. In

this way, the arcing horns and fingers prevent pitting of the contacts 51 and blade 50 when an arc is formed upon the switch being opened or closed.

It will be observed that the fingers or horns 88 and 89 are offset at their central portions and crossed to provide a stop or shoulder for engagement by the fingers 97, and at the same time, provide relatively great resiliency because of their length. Sidewise play is thereby permitted without any dislocation of the stop or shoulder.

Upon opening of the blade, the blade 50 and horns 97 swlng back until the mechanism is stopped. The horns 97 and connected block 92, whi back because of inertia and thereby provi e a highly effective means for breaking any are which may exist between said horns 97 and horns 88, 89.

In the operation of the switch let us assume that it is to be used as a disconnect switch and that the circuit breaker or oil switch has first been opened. The switch may then be opened by rotating the rotary insulator 18 through means of a crank (not shown) connected to the shaft 19 or by means of a pipe extension 20 connected thereto. When the insulator 18 is rotated, the block 24 connected to the top thereof will also be rotated. The lower end of the carriage 41 being connected to the block 24 through the connecting rod 44 said carriage will be rocked clockwise about the pin 40 upon the rotation of the insulator 18. During the initial movement of the carriage 41, the blade 50 will be drawn substantially in thedirection of its length and during such movement the spring 59 which is already compressed enough to keep the blade extended its maximum length with the pin 57 abutting the stop 60, will be compressed further and will act on the blade as soon as the latter is free reached the limit of its movement said bladewill occupy the dotted line position of Figure 1. As shown in Figure 5, a 135 rotation of the block 24 will be suflicient to bring the carriage 41 to the limit of its opening movement. The movement is limited by a suitable stop on the operating mechanism (not shown).

When it is desired to close the switch, it is only necessary to rotate the rotary insulator in the other direction causing the carriage 4.1,to rock counter-clockwise about the pin 40. In closing, there is no tendency for the torsion spring 59 to compress as the inertia of the blade 50 acts with said spring to keep said blade extended its maximum effective length with the pin 57 abutting the stop 60. For this reason the blade 50 will strike full into the contact 51 and will knock out any ice accumulation. Due to the construction of the contacts 68 they collapse when the switch is open and no ice will accumulate between them except in the divergent portion and this is readily dislodged. The bumper comprising thecap 80 and the sprin 84 on the stem 78 will act to break the fall of the blade 50 and the latches 82 will engage over the pin 87 and hold the said blade in the contact 51 thus preventing said blade from being thrown out of said contact by excessive slamming or from any magnetic effect.

When the blade is again opened, the initial substantially longitudinal movement of the blade 50 will act to release the pin 87 from beneath the latches 82 so as to permit a subsequent swinging movement of said blade.

We are aware that many changes may be made and many details varied throughout a wide range without departing from the principles of this invention and we do not propose limitin our invention to the details shown or descri d.

We claim 1. In a switch, the combination comprising a switch terminal, a pivoted switch arm adapted to be projected into engagement with said terminal, a spring bumper for breaking the fall of said arm, and latches mounted on said bumper for locking said arm thereto. 2. In a switch, the combination comprising a switch terminal, a pivoted switch blade adapted to be projected into engagement with said terminal and having laterally extending lugs thereon, and a spring bumper for breaking the fall of said blade and havwith said lugs for locking said blade on said bumper.

3. In a switch, the combination comprising a switch terminal, a pivoted retractable arm adapted tobe projected into engagement with said terminal, a spring bumper disposed adjacent said terminal for breaking the fall of said arm, latches on said bumper adapted to engage with said armfor locking the same thereto and means for retracting said arm for releasing the same from said latches.

4. In a switch, the combination comprising a switch terminal, a retractable arm adapted to be projected into engagement with said terminal, a spring bumper for breaking the fall of said arm, latches on said bumper adapted to engage with said arm for locking the same thereto, said latches being operable in the direction of said arm and means for retracting said arm in the direction of its length to release the same from said latches.

5. In a switch, the combination comprising a switch terminal, a pivoted switch arm adapted to be projected into engagement with said terminal, a bumper for breaking the fall of said arm, a spring for supporting said bumper, latches mounted on said bumper for locking said arm thereto, and a spring indeg pendent of said first spring for normally holding said latches in operable position.

6. In a switch, the combination comprising a switch terminal, a pivoted switch arm adapted to be projected into engagement with said terminal, a bumper for breaking the fall of said arm, a spring for supporting said bumper, latches mounted on said bumper for locking said arm thereto, and a separate spring for normally holding said latches in operable position.

7. In a switch, the combination comprising a switch terminal, a retractable arm adapted to be projected into engagement with said terminal, a bumper for breaking the fall of said arm latches mounted on said bumper for locking said arm thereto, a spring for suppprting said bumper, a separate spring for normally holding said latches in operable position, and means for retracting said arm for releasing the same from said latches.

8. In combination, an arm pivoted intermediate its ends, a switch blade pivoted at one end to one end of said arm, a torsion spring disposed about the pivot of the blade and urging said blade in opening direction,

and means connected to theother end of the arm for rocking said. arm about its ivot.

9. In combination, an arm pivote intermediate its ends, a switch blade pivoted at one end -to one end of said arm, a torsion spring disposed about the pivot of the blade and urging said blade in opening direction, a terminal member cooperating with the blade at the other end thereof, latch members adj acent the terminal member, the blade having elements coacting with the latch members for locking the blade closed, said latch members opening in the direction of the length of the blade and toward the pivot thereof, and means connected to the other end of the arm for rocking said arm about its pivot.

10. In an electric switch, a stationary 1nsulator, a rotary insulator, bracing means between the two, a relatively short link carried adjacent to the stationary insulator, and means pivoted to the link and to the rotary insulator whereby a rotation of the insulator produces a rotation of the link, abutment means rotated with the link and a relatively long switch blade pivotally mounted on the link and engaged by the abutment means after a predetermined rotation of the llnk to have successive rotary and rectilinear movement upon the rotation of the link to the switch open position.

11. In an electric switch, a stationary insulator, a rotary insulator, bracing means between the two, a relatively short link carr ed adjacent the stationary insulator, means pivoted to the link and to the rotary insulator whereby a rotation of said insulator produces a rotation of the link, abutment means rotated with the link, a relatively long switch blade pivotally mounted on the link and engaged by the abutment means after a predetermined rotation of the link to have successive rectilinear and rotary movement upon the rotation of the link to the switch open position, and means for imparting a movement to the blade with reference to the link in a direction opposite to'the first rectilinear movement,

said means being effective upon the com m'encement of the rotary movement to theswitch open position, whereby the subsequent closing movement of the switch is effective by a rotary motion.

12. In combination, two stationary insulators, a contact member carried by one of said insulators, a movable switch member cooperating therewith mounted adjacent the other insulator, a rotary insulator disposed between the stationary insulators, means including an operating member rotated by the rotation of the last mentioned insulator for moving the movable switch member, first longitudinally, abutment means for thereafter positively swinging said switch member away from the contact member, and means efl'ective respon- 65 sive to the initiation of the swinging movement for moving the switch member away from the abutment means.

13. In combination, two stationary insulators, a contact member carried by one of said insulators, a movable switch member cooperatin therewith mounted adjacent the other insu ator, a rotary insulator disposed between the stationary insulators, means including an operating member rotated by the rotation of the last mentioned insulator for moving the movable switch member first longitudinall and abutment means for thereafter positive y swinging said switch member away from the contact member.

14. In an electric switch, a stationary insu1ator,a rotary insulator, a protecting housing supported by both insulators, a relatively short link pivotally mounted on the housing, a relatively long switch blade pivotally mounted on the link, and operating mechanism within the housing and including a portion of said link extending outside of the housing for operating the switch blade upon rotation of the rotary insulator.

15. An electric switch comprising a stationary insulated member, means including a rotatable insulator for supporting said member, a switch supporting link pivoted on said member, a relatively long switch blade pivoted on said link at a relatively short distance from the pivot of said link, cooperating means between the blade and the link for limiting the relative movement between them, connecting means between the link and the rotary insulator for rotating the link upon rotation of the insulator, and means for limiting the relative movement between the link and the blade upon the actuation of the link to open'the switch, whereby the blade is first given a rectilinear motion and thereafter is rotated with said link.

16. An electric switch comprising a stationary insulated member, a switch supporting link pivoted on said member, a relatively long switch blade pivoted on said link at a 'relativel short distance from the pivot of said lin cooperating means between the blade and the link for limiting the relative movement between them, a rotary insulator, connections between the link and the rotary insulator for rotating the link upon rotation of the insulator, and means for limiting the relative movement between the link and the blade upon the actuation of the link to open the switch, whereby the blade isfirst given a rectilinear motion and thereafter is rotated with said link.

17. In a switch structure of the character described, a blade, a stationary contact, a support, links pivotally connected to the blade and to the support, the links and the blade having cooperating means permitting the blade to be withdrawn lengthwise from the contact and thereafter causing the blade to be moved with the as a unit into open position, means acting in the continued opening movement of the blade to return said blade to its initial relation to the links, the first mentioned means acting to cause movement of the blade with the links as a unit during closing of said blade, and means for exerting endwise pull on the blade away from the contact.

18. In a switch structure of the character described, a blade, a stationary contact, a support, links pivotally connected to the blade and to the support, the links and the blade having spaced abutments permitting limited movement of the blade about the pivotal connection between the same and the links during the first portion of the opening movement of said blade, means acting in the continued opening movement of the blade to return said blade to its initial relation to the links, the first mentioned means acting to cause movement of the blade with the links as a unit during closing movement of the blade, and means for exerting endwise pull on the blade away from the contact.

19. In a switch structure of the character described, a support, a blade member, a fixed contact, means for exerting endwise pull on the blade away from the contact, linkage connections between the support and the blade member at the end thereof remote from the contact and acting to raise said end of the blade at the initiation of said endwise pull causing rocking of the other end of the blade in the contact and breaking the blade away from the contact, said connections permitting substantially rectilineal withdrawal of the blade from the contact and causing sub sequent swinging movement of the blade into open position, the linkage connections causing the blade to be swung into closed position when said blade is' subjected to pressure toward the contact.

In witness whereof, we hereunto subscribe our names this 23rd day of September, 1926.

ALFRED ALSAKER. ERIC NORDHEM. 

